1. Field of the Invention
This invention relates to a stereomicroscope for use in surgical operation and the like that a plurality of observers views an object at once.
2. Description of the Prior Art
Recently, for the purposes of education and so on, stereoscopic microscopes have been largely used through which a plurality of persons can observe an object at the same time and with nearly the same magnification.
As one of methods to realize it, there is a observation through a stereoscopic TV. As an example, it has been proposed by Japanese Patent Preliminary Publication No. Hei 1-319721. This example, as depicted in FIG. 1, is designed so that for the stereoscopic view of the stereomicroscope, a pair of imaging optical systems are divided into two optical systems to mount TV cameras at their imaging position, images obtained from the TV cameras on both sides are alternately reproduced on a monitor by a switcher, and the image of the right optical system is observed with the right eye, while that of the left optical system with the left eye. Specifically, light from an object O, after passing through an objective lens 22 and individual variable magnification optical systems 23L and 23R on both sides, is split by beam splitters 24L and 24R so that one of the split light travels in straight lines, traverses imaging lenses 25L and 25R, and is observed as magnified images at eyepieces 26L and 26R, while the other is laterally reflected 90.degree., passes through imaging lenses 27L and 27R, is further reflected 90.degree. upward from planar mirrors 28L and 28R, and imaged on imaging surfaces 29L and 29R of TV cameras 30L and 3OR. The images transmitted from the TV cameras 30L and 30R are alternately displayed on a monitor 32 by a switcher 31. By a scope 33 having shutters 33L and 33R opened and closed in synchronization with the switcher 31, the images of the right and left optical systems are alternately observed with the right and left eyes for the stereoscopic vision.
Japanese Patent Preliminary Publication No. Sho 63-143519 shows the arrangement that, without using any image sensory two sets of first and second stereoscopic observation optical systems and an illumination system for illuminating an object to be detected are disposed behind an objective lens used in common, in which an optical axis deflecting means for the second stereoscopic observation optical system is provided in the vicinity of the pair to the first stereoscopic observation optical system and optically combined with the second stereoscopic observation optical system.
The Hei 1-319721 prior art, however, has developed the defect that a second observer, who does auxiliary work while viewing the picture image of a stereoscopic TV, is hard of work because the stereoscopic TV displays an image viewed from a first observers's observation point. Moreover, the work they must do while viewing the picture image makes their postures unusual and causes difficulty in operation for a long time. In the sho 63-143519 prior art, to prevent mutual interference between two sets of observation optical systems incorporated in the microscope body, oversizing of the microscope body is caused, with resultant inconvenience to operation.
Where the work done making use of the stereomicroscope is complicated and needs accuracy, it is often desired that a plurality of operators does the work in cooperation with one another. Particularly when the steromicroscope is a surgical microscope, under observation through which a surgical operation is to be performed as a cooperative work by a first observer who principally performs the operation and a second observer who aids the operation the two observers should observe an object O in the same situation as far as possible. In other words, it is required that they can obtain the same visual field for observations with the same magnification for observations.
Further, some surgical technique would require that the observers change their relative positions with respect to the object O (in other words, observers' observation directions) during the operation; microscopes meeting such requirement are awaited.
In the past, the stereomicroscope realizing the demands mentioned above has been set forth in Japanese Patent Preliminary Publication No Sho 47-41473, for instance. Referring to FIGS. 2A and 2B, FIG. 2A is a front sectional view and FIG. 2B is a side view. In this stereomicroscope, a pair of variable magnification optical systems 42 is disposed behind a single objective lens 41 located above an object O, and a beam of light passing through the variable magnification optical systems 42 is divided by an optical path splitting member 43 and introduced into a pair of observation optical systems 44 disposed on opposite sides. Two observers can thus observe stereoscopically the object O of the same situation, facing toward each other.
As another measure, the stereomicroscope shown in FIGS. 3A, 3B and 3C is set forth in Japanese Utility Model Publication No. 55-39364. This arrangement is such that at least three sets of variable magnification optical systems 45 located behind the objective lens 41, namely in the figures, two pairs of variable magnification optical systems 45 are disposed to intersect at an angle of 90.degree. with each other and introduces light into two observation optical systems 44. Hence, the first and second observers can observe the object O in the same situation, even from the directions making right angle with each other.
As still another measure, the stereomicroscope depicted in FIG. 4 is stated in Japanese Patent Preliminary Publication No. Hei 2-143215. In this stereomicroscope, an optical path splitting means 48 is disposed in the optical path between a single objective lens 46 and a pair of variable magnification optical systems 47, and another pair of variable magnification optical systems 49 is disposed in the optical path of a part of the light beam split by the optical path splitting means 48 so that two observers can view stereoscopically the object O through the observation optical systems 44. Furthermore, by rotating the optical system including the variable magnification optical systems 49, the angle defined between the two observers' observation directions can be arbitrarily set.
The arrangement of the stereomicroscope shown in FIG. 2A, however, has a drawback that the angle between the two observers' observation directions is limited to 180.degree. cannot be set at any other angle.
For the arrangement in FIGS. 3A, 3B and 3C, the number of the variable magnification optical systems 45 is so large that numerous lenses must be moved when magnification is changed. Accordingly, a mechanism for changing magnification gets complicated, which raises problems such as difficulty of adjustment and increase in size, weight and cost of the microscope there is also the problem that the angle defined by the positions of the two observers is limited to 90.degree..
As for the arrangement in FIG. 4, although the positions of the two observers can be arbitrarily changed, another pair of variable magnification optical systems must be provided on the optical system of the reflected beam, which fact has the defect that the microscope is brought to oversizing, an increase of weight, and high cost. Further, to put two images to be observed in identical magnification, an interlocking mechanism is required for associating individual variable magnification optical systems with each other, on the condition that the position of the second observer can be altered with respect to the position of the first observer. This has the defects that the arrangement is complicated and the cost is raised.